The present invention relates to an apparatus for cleaning and/or decontaminating polyester, in particular polyethylene terephthalate (termed PET hereinafter). PET is one of the most used polyesters. PET has many uses, but is primarily used in the beverage industry as material for beverage bottles.
Especially in the case of beverage bottles, in order to be able to reuse the PET even after use of the bottles and/or contamination of the bottles, processes have been developed in the prior art which enable recycling of polyester. After this recycling the cleaned or decontaminated polyester or PET can be reused for manufacturing beverage bottles, for example.
Such processes are disclosed, for example, in PCT/US99/23206. In these known processes the PET to be recycled is first comminuted into small flakes. The comminuted PET is then placed in water in order to be able to separate lighter materials, such as paper and the like, from the PET by skimming them off from the water surface. The PET is then dried by the action of heat. After drying, the treated PET is mixed with an alkaline material. This mixture is also dried by heat. In the subsequent central reaction step, the PET which has been mixed with alkaline material and dried in this manner is saponified until the alkaline material added has been completely used up with constant further drying under the action of heat. The reaction products produced by the saponification are then separated, as a result of which cleaned PET is produced.
In order to obtain a satisfactory yield of recycled PET by the above-mentioned process, it is necessary that the central reaction step takes place essentially in an anhydrous environment. The rotary furnaces which are used for this central reaction step and which are known from the prior art, for example the Rotary Calciner, from Heyl & Patterson Inc., however, are only able to provide such conditions with restrictions.